A study is proposed to determine the relative effects of the nature of a biomaterial, shear stress, blood temperature, pH and gas content on inducing the degradation of blood that occurs when it contacts a biomaterial. Injection moldable and discardable blood exposure devices will be used that limit blood contact to a single material (or surface) without an air interface and permits complete control of shear rate and temperature. The exposed blood will be studied for changes in a number of parameters including mean red cell volume and volume distribution, red cell membrane ion permeability, plasma hemoglobin content and extent of plasma protein denaturation.